Minisplit refridgerant piping

Discussion in 'HVAC Heating & Cooling' started by CheesecakeLover, Apr 11, 2021.

  1. CheesecakeLover

    CheesecakeLover New Member

    Joined:
    Jan 6, 2018
    Location:
    Hopatcong, NJ
    Hello, this is in regards to a minisplit installation. The instructions aren't clarifying things for me.
    1. I have read online that there is a minimum line length for the line, but the document does not say anything about minimum length. Does it hurt efficiency to cut off excess tubing and re-flare?
    2. Are there any slope requirements with the refrigerant piping that it must only run down hill? (I know the drain pipe does need to stay sloped.)

    [​IMG]
     
  2. WorthFlorida

    WorthFlorida The wife is still training me.

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    Retired
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    Orlando, Florida
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  4. fitter30

    fitter30 Well-Known Member

    Joined:
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    Occupation:
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    Location:
    Peace valley missouri
    There is no minimum line lenght but shorter might 10' might create little vibration. Refrigerant piping doesn't have to be pitched. Just don't go over factory recommendations for max lenght and height. Use factory supplied flare nuts not the ones on line set.
     
  5. fitter30

    fitter30 Well-Known Member

    Joined:
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    Retired service tech
    Location:
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    Need brand and model of your mini ever brand can be different it will say in the install manual. Refrigerant piping doesn't have to be pitched. Just don't go over factory recommendations for max lenght and height. Use factory supplied flare nuts not the ones on line set.
     
  6. Dana

    Dana In the trades

    Joined:
    Jan 14, 2009
    Location:
    01609
    While slope isn't required, there are apparently (rare but real) instances of vapor-locking reported when coiling up the excess in multiple loops standing on edge (the plane of the loop parallel to the wall) rather than flat (loop plane parallel to the floor or ground).

    Coiling rather than cutting to length is pretty standard when using the DIY pre-charged linesets eg:

    [​IMG] [​IMG]
    [​IMG]
    ^Not best practice^


    -------------------------------------


    Better practice:

    [​IMG]
    ^^Vapor locking pretty much can't happen if the excess coils are set up parallel to the ground.^^

    Of course the best approach is to cut the lines to length, but not always within the skill/tool set of DIYers.
     
  7. WorthFlorida

    WorthFlorida The wife is still training me.

    Joined:
    Oct 28, 2009
    Occupation:
    Retired
    Location:
    Orlando, Florida
    Dana, very true, what I don't know is are the lines sealed up with a vacuum just before connecting them. If not too much moisture can get in the lines thought there is a dryer in the system. Bottom line for DIYer's mini-splits lines should be cut, flared and the lines placed under a vacuum.
     
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